engine light on has a code 1211 it means preasure of injectors is higher or lower than desired
check engine light on 1996 Ford F-350
You have to find out if your 1211 is actively occuring, or in memory. If it is in memory only, it is either an oil condition issue (change oil), or you have a faulty ICP sensor. (ICP = Injection Control Pressure)
There is little you can do yourself to repair this code at home without special tools and equipment. My notes say possible causes are leaking fuel injector seal, low reservoir oil , defective IPR valve, defective ECM or wiring, and faulty high pressure oil pump.